Spacer element for the attachment of a sheet metal part, component assembly and method for its manufacture

ABSTRACT

A spacer element which is designed at both ends for the attachment to a sheet metal part or to a hollow section for the formation of a component assembly and which optionally has a fastener section with an internal thread or external thread for the attachment of a component to the component assembly by means of a screw or a nut, is characterized in that the spacer element is not deformable or at least substantially not deformable on attachment to the sheet metal part or to the hollow section and in that the spacer element is provided at both end faces with respective undercuts for the form-fitted reception of sheet metal material or of the wall material, whereby the spacer element is secured to the sheet metal part or to the hollow section and preferably also secured against, rotation. Various variants, component assemblies and methods are likewise described and claimed.

This application is a divisional of U.S. patent application Ser. No.12/606,184 filed Oct. 26, 2009, which claims the benefit of priorityfrom German Patent Application No. DE 10 2008 053 346.7, filed on Oct.27, 2008, the contents of all of which are incorporated herein byreference.

The present invention relates to a spacer element which is designed forattachment to a sheet metal part for the formation of a componentassembly and also to a corresponding component assembly and a method ofmanufacture of such a component assembly.

A spacer element of this kind is known from EP-B-1068458. There thespacer element is designed at both ends for the attachment to a sheetmetal part for the formation of a component assembly and has a fastenersection with an internal thread or an external thread for the attachmentof a component to the component assembly by means of a bolt or a nutrespectively. The spacer element is used there in the hollow cavity of asheet metal part which is normally defined by two sheet metal partswhich are welded together for the formation of the hollow cavity. Suchsheet metal constructions are frequently met in motorcar construction orin coachwork, for example in the manufacture of frame parts, sills andpillars. Such spacer elements bring about a stiffening to thecorresponding component and enable in addition the attachment of afurther component to the component assembly. For example by way of thespacer element a door hinge, a pivot device for a safety belt or a wheelsuspension can be attached to such a spacer element i.e. to the partstiffened by it and having a hollow cavity.

The hollow cavity need not necessarily be formed by two sheet metalparts welded to one another but rather can be formed by the hollowcavity of a hollow section or tube, far example a tube with rectangularcross-section, the spacer element could then connect two oppositelydisposed wall sections of the tube. It is however also known to secure aspacer element of this kind only at one of its two ends to a wallsection of a sheet metal construction forming a hollow cavity with theinner side of the oppositely disposed wall section contacting the otherend of the spacer element. When a component is screwed onto the outerside of the oppositely disposed wall section, for example by a boltwhich is screwed into the internal thread of a spacer element, theoppositely disposed wall section is clamped between the free end of thespacer element and the component so that a firm connection of the spacerelement at the oppositely disposed wall section is superfluous, assumingthat the corresponding bolt is correctly tightened to secure thecomponent.

Thus two cases can he distinguished. Either the spacer element isconnected at two ends in form-fitted manner to two oppositely disposedwall sections defining a hollow cavity between them or is connected inform-fitted manner only at one end to one of the opposing wall sections,with the spacer element only contacting the other wall section.

With the known spacer element the form-fitted connection takes place bya riveting process such that a rivet section provided at each end faceof the spacer element is re-shaped into a rivet bead. An advantage ofthe above-named spacer element in comparison to other known mechanicallyjoined spacer elements lies in the fact that it is so designed that thedesired spacing can be relatively accurately maintained.

The object of the present invention is to provide a different type ofspacer element and also component assemblies and methods for theirmanufacture which enable an even more precise observation of a pre-setspacing and which in addition ensure a flat screwed joint surfacerelatively free of distortions and deformations and which is intended tohave excellent security against rotation, with the spacer elementhowever being able to be manufactured at favourable costs and havinggood mechanical characteristics.

In order to satisfy this object there is provided, in accordance withthe invention and a first aspect of the present invention a spacerelement which is designed at both ends for the attachment to a sheetmetal part or to a hollow section for the formation of a componentassembly and which optionally has a fastener section with an internalthread or external thread for the attachment of a component to thecomponent assembly by means of a screw or a nut, with the spacer elementbeing characterized in that it is not deformable or at leastsubstantially not deformable on attachment to a sheet metal part and inthat the spacer element is provided at both end faces with respectiveundercuts for the form-fitted reception of sheet metal material, wherebythe spacer element is anchored to the sheet metal part and preferablyalso secured against rotation.

This aspect of the invention can be used both for a spacer element whichis used to secure a component to a component assembly but also forspacer elements which are to have a pure spacer function and accordinglydo not require a fastener section. In the latter case it is favourablewhen the spacer element is secured at both end faces to sheet metalparts.

In accordance with the second aspect of the present invention there isprovided a spacer element which is designed at one end for theattachment to a sheet metal part or to a hollow section for theformation of a component assembly and which optionally has a fastenersection with an internal thread or external thread for the attachment ofa component to the component assembly by means of a bolt or a nut, withthe special characterization that the spacer element is not deformableor at least substantially not deformable on attachment to the sheetmetal part and that the spacer element is provided at one end face withat least one undercut for the form-fitted reception of the sheet metalmaterial of the wall material, whereby the spacer element is anchored tothe sheet metal part and preferably secured against rotation.

In the designs in accordance with the two aspects of the invention thespacer element, which is not deformable always has the same length bothbefore and also after the attachment of a sheet metal part so that thedesired spacing between the two oppositely disposed all sections of thesheet metal part or of the hollow section defining the hollow space canbe precisely maintained. This advantage can only be achieved withreservations using a spacer element which is attached at its two ends tocorresponding wall sections by re-shaping corresponding rivet sectionsof the spacer element. Furthermore, by the forming of the material ofthe wall sections into respective recessed mounts of the spacer elementa planar screwed joint surface is provided whereby the attachment of afurther component to the component assembly formed by the spacer elementand the sheet metal part is substantially simplified.

The spacer element preferably has a central recess within a ring-likecontact surface at one or at each end face and also at least oneundercut in the sidewall of the recess.

The undercut can be a ring-like undercut and/or the sidewall of thecentral recess can extend at least substantially obliquely to thelongitudinal axis so that the recess has in an axial section, i.e. aplane containing the longitudinal axis, optionally the form of a concavethroat, with an at least substantially conical shape, optionally aconcavely or convexly rounded arched shape, with a rounded transitionpreferably being present at the end face of the spacer element from thering-like contact surface to the central recess.

An embodiment with only one ring-like undercut in each recess iscompletely simple to manufacture but offers itself no pronouncedsecurity against rotation so that such a security against rotation,which is necessary with a spacer element with a fastener elementfunction (not however with a pure spacer element) must be achieved bother measures such as noses and/or recesses providing security againstrotation. This can he particularly favourably brought about by a spacerelement which has a plurality of recesses spaced from one another or agroove of wave-shaping plane view in the ring-shaped contact surfacewhich form corresponding discrete undercuts in the sidewall of thecentral recess, with both the recesses and the wave-shaped groove andthe projections of the sidewall formed by them or by it, which form theundercuts, also serving for the security against rotation.

In other words the spacer element in this example has a formation atboth end faces which correspond to a so-called RSU element of thepresent applicants as described in EP-B-759510 and in EP-B-957273.

The spacer element can have, a smooth pierced cylindrical bore or holewhich is optionally designed to receive a thread forming or threadcutting bolt. I.e. the thread does not have to he pre-cut but can beproduced after the installation of the spacer element into the hollowcavity during screwing on of the further component by means of thecorresponding bolt. The excellent, security against rotation which isachieved at both ends of the spacer element ensures that rotary slippageof the spacer element is precluded.

The spacer element preferably has elongate features providing securityagainst rotation such as noses and/or recesses which extend in radialplanes, i.e. planes perpendicular to the longitudinal axis, and whichare preferably provided at the sidewall of the ring-like recess. Suchfeatures providing security against rotation are simply manufactured andensure excellent security against rotation, i.e. prevent the spacerelement turning relative to the sheet metal part, for example when abolt is screwed into or out of the spacer element.

A further embodiment is characterized in that the spacer element isrectangular or square in axial cross-section and has two bars at the oneend face or at both end faces which extend parallel to one another andto the neighbouring side of the spacer element and form respectiveundercuts at the two mutually confronting sides. Rectangular elementshaving such a shape at one end face are known as fastener elements buthave not hitherto been used as spacer elements.

A further embodiment of the initially named kind in accordance with theinvention is characterized in that the two bars are formed by respectivegrooves and in that preferably both sides of each groove each have arespective undercut.

The invention will subsequently be explained in more detail withreference to embodiments and to the drawings in which are shown:

FIG. 1A a perspective representation of a first embodiment of a spacerelement in accordance with the invention,

FIGS. 1B, 1C an attachment of the element in accordance with theinvention of FIG. 1A in the hollow cavity of a sheet metal part or of ahollow section,

FIG. 1D the completed component assembly,

FIGS. 2A-2D diagrams which correspond to the FIGS. 1A-1D but of adifferent spacer element in accordance with the invention,

FIGS. 3A-3D diagrams which correspond to FIGS. 1A-1D but of anotherspacer element in accordance with the invention,

FIGS. 4A-4D diagrams which correspond to FIGS. 1A-1D but of anotherspacer element in accordance with the invention,

FIGS. 5A-5D diagrams which correspond to FIGS. 1A-1D but of anotherspacer element in accordance with the invention, with the additionalFIG. 5E showing a partly cut away perspective representation of thecompleted component assembly in accordance with FIG. 5D,

FIGS. 6A-6D diagrams which correspond to FIGS. 1A-1D but of a differentspacer element in accordance with the invention, and

FIGS. 7A-7D diagrams which correspond to FIGS. 1A-1D but of anotherspacer element in accordance with the invention.

Referring to FIG. 1A a first spacer element 10 in accordance with theinvention is shown there which is designed at both ends 12, 14, i.e. atthe end faces, for the attachment to a sheet metal part 16 or to ahollow section 18 (FIG. 1B) for formation of a component assembly 20(FIG. 1D). The spacer element shown here has a central bore 22 and isintended as a pure spacer element, i.e. it has no fastener section. Itwould however be entirely possible to provide the spacer element with afastener section with an internal thread or an external thread for theattachment of a component to the component assembly by means of a boltor a nut respectively or to design the central bore 22 in such a waythat it can receive a thread forming or thread cutting bolt. In thesetwo latter case the spacer element will then not only have the functionof a spacer element but rather it could also serve for the attachment ofa further component 24 to the component assembly by means of thecorresponding bolt 26. The attachment of such a component will also bepossible with a bolt which is passed from one side through the componentand the bore and is secured at the other side of the hollow section ofthe sheet metal part by a nut. When it is stated here that the spacerelement is provided with an external thread in the fastener section thenthis is to be understood in such a way that a shaft part having a threadprojects from one end face of the spacer element and is surrounded atthis end face by a contact surface and optionally a ring recess with anundercut or a plurality of undercuts, with the shaft part projectingthrough a hole in the wall of the sheet metal part or of the hollowsection.

The spacer element 10 is at least substantially not deformable on theattachment to a sheet metal part 16 or to a hollow section 18. At thetwo end faces 12, 14 the spacer element is provided with respectivering-like undercuts 28 for the form-fitted reception of a sheet metalpart, whereby the spacer element 10 is secured to the sheet metal part16 or to the hollow section 18. The attachment can also be executed in amanner secure against rotation and indeed by noses 30 providing securityagainst rotation (and/or recesses providing security against rotation)which are provided here in radial planes, i.e. in planes perpendicularto the longitudinal axis, at a sidewall 32 of a central cut-out orrecess 33 containing the undercut 28, with a corresponding centralcut-out or recess 33 which is surrounded by respective ring-like contactsurfaces 12A and 14A being provided at both ends 12, 14 of the spacerelement 10.

Various methods are possible for the manufacture of a component assemblyin accordance with FIG. 1D which will now be explained with reference toFIGS. 6A to 6D. Although the spacer element 10 in accordance with FIGS.6A to 6D is designed differently from the spacer element 10 inaccordance with FIGS. 1A to 1D the concepts explained here apply exactlyin the same way for the embodiment of FIGS. 1A to 1D and for all furtherspacer elements in accordance with FIGS. 2 to 5 and 7. In FIG. 6A afirst sheet metal part 16A is attached to the first end face 12 of aspacer element 10 by means of a first die button 40 which presses thesheet metal material in form-fitted manner into the correspondingundercut or undercuts 28 of the first end face 12.

The use of the die button 40 in accordance to FIG. 6B preferably takesplace in a press in conjunction with a plunger 42 of a setting headwhich receives the spacer element 10, with the setting head having acut-out 44 which is dimensioned such that it fully receives the spacerelement 10 and the lower end face 12 of the element lies in a plane withthe lower end face 47 of the plunger 42. The die button 40 can forexample be arranged at the lower tool of a press or at the intermediateplatten of the press whereas the setting head or the plunger 42 isarranged at the intermediate platten of the press or at the upper tool.An inverted arrangement is also possible, i.e. the die button 40 can bearranged facing downwardly at the upper tool of the press or at theintermediate platten of the press whereas the setting head or theplunger 42 is arranged facing upwardly at the intermediate platten ofthe press or at the lower tool respectively.

During the closing of the press the die button 40, i.e. the die buttonprojection 41 presses the sheet metal material into the undercuts 28.The attachment of the spacer element 10 to the sheet metal part 16A canalso take place in a station of a progressive tool, for example in anarrangement, where the hole 46 in the sheet metal part 16A is piercedout in an earlier station of the progressive tool (insofar as the diebutton 40 is not itself used for this purpose as will be later explainedin more detail). It is evident also that the die button 40 has twoparallel noses 48 which are obliquely set at their outer sides. In thisway the sheet metal material is pressed in a form-fitted manner into theundercuts 28. Alternatively to the use of the die button in a press aso-called C-frame can be used. In an arrangement of this kind either thedie button or the plunger is fixedly held at one side of the opening ofthe C-frame whereas the other respective part, i.e. the plunger or thedie button, is hydraulically biased in order to achieve the press-infunction.

As shown in FIG. 6C a second sheet metal part 16D is subsequentlyarranged at the second end face 14 of the spacer element 10. By means ofa second die button 40 or, on turning over the component assembly, bymeans of the first named die button 40, material of the second sheetmetal part 16B is pressed in form-fitted manner into the correspondingundercut or undercuts 28 of the second end face 14. The first and secondsheet metal parts 16A, 16B are then connected together or to at leastone further sheet metal part for the formation of a hollow cavity 54 byother means, for example by spot-welding, mechanical joining or byfurther fastener or indeed spacer elements. In this example this otherconnection takes place after the attachment of the second sheet metalpart to the second end face of the spacer element. It is however alsostraightforwardly possible to first secure the two sheet metal parts toone another and to subsequently introduce the spacer element into the soformed hollow cavity 54 as is for example shown with reference to FIGS.1A to 1D or FIGS. 7A to 7D.

In FIGS. 1A to 1D the spacer element 10 is inserted into the hollowcavity 54 of a hollow section 18 or of a sheet metal part 16 whichconsists of at least one first sheet metal part 16A and one second sheetmetal part 16B which are joined together or with at least one furthersheet metal part (not shown) for the formation of a hollow cavity, atpositions 50, 52 remote from the spacer element for example byspot-welding, mechanical joining or by further fastener elements orspacer elements. The first and second end faces 12, 14 of the spacerelement 10 lie opposite respective first and second wall sections 17A,17B of the hollow space 54. By means of a suitable die button 40 thespacer element is attached at the first end face 12 to the first wallsection 17A having a pre-manufactured hole in such a way that the diebutton 40 presses material of the first wall section 17A which surroundsthe hole 46 into the corresponding undercut 28 of the first end face inform-fitted manner. By means of a second suitable die button 40 thespacer element 10 is attached at the second end face 40 to the secondwall section 17B, which likewise has a hole 46, in that the die buttonpresses material of the second wall section 17B which surrounds the hole46 into the corresponding undercut 28 of the second end face 14 inform-fitted manner. This attachment can take place in different ways. Inaccordance with a first possibility first and second die buttons 40 areused for the pressing of the first and second wall sections 17A, 17Bwhich—shown in FIG. 1B if one assumes that the upper die button 40 shownthere in broken lines is provided in correspondence with the lower diebutton 40 with a die projection 41—simultaneously takes place fromopposite directions in a pressing device. Alternatively to this the onedie button, for example the lower die button 40 in FIG. 1B can be used,whereas the upper die button 40 in accordance with FIG. 1C is first usedat a later point in time in order to press the material of the wallsection. 17B into the upper end face 14 of the spacer element. Thissequential pressing of wall material into the end faces 12, 14 of thespacer element 10 can take place in one or in more pressing devices, intwo stations of a progressive tool. Finally, only one die button 40 canbe used when the component assembly is turned over between individualpressing operations.

The form of the die button projection 41 of the die button(s) 40 inaccordance with FIGS. 1B and 1C is adapted to the shape of the centralrecess 33 with undercuts 28, whereby sheet metal material or wallmaterial is pressed into respective undercuts. At the same time sheetmetal material i.e. wall material is pressed over the noses 30 providingsecurity against rotation and/or into any recesses providing securityagainst rotation so that the features providing security againstrotation are in form-fitted engagement with the sheet metal material orwall material. Strictly speaking one could in this embodiment dispensewith a ring-like undercut 28 since the noses and/or recesses providingsecurity against rotation themselves form local undercuts. Actually, fora spacer element the undercut could be omitted altogether because theconstraint on axial movement of the spacer can be generated by the twooppositely disposed sides or walls defining the hollow cavity.

The die button projection 41 has here a generally conical shape andconsists specifically of a radius 62 in the region of the surroundingend face of the die button, a conical section 64 into which the radius62 merges gently, a general cylindrical intermediate section 66 andfinally a further conical section 68. Since no undercuts are present atthe die button projection 41 the finished component assembly inaccordance with FIG. 1D can be straightforwardly drawn from the diebutton 40 of the buttons 40 on opening of the pressing device.

These different variants of the use of the die button 40 apply for allfurther embodiments, which is why the same reference numerals will beused for the same parts and have the same meaning unless something tothe contrary is stated. This statement applies not only to the diebuttons but rather also for all features of the spacer elements,component assemblies and method described here.

As already explained above the spacer element 10 of FIG. 1A has aring-like recess 32 at each end face 12, 14 within a ring-like contactsurface 12A, 14A as well as at least one undercut 28 in the sidewall ofthe recess 32.

As likewise already brought out above it is also possible to attach thespacer element at only one end face to one sheet metal part or to onewall section or hollow cavity providing the spacer element 10—as shownin FIGS. 2A to 2D—has a fastener section with an internal thread or anexternal thread (not shown) for the attachment of a component 24 to thecomponent assembly by means of a bolt 25 or a nut respectively. Here thespacer element is at least substantially not deformable on attachment toa sheet metal part and is also provided here at one end face 12 with atleast one undercut 28 for the form-fitted reception of the sheet metalpart, whereby the spacer element is anchored in a manner secure againstrotation at the sheet metal part.

Specifically a plurality of undercuts 28 are provided here which areformed in that a plurality of mutually spaced-apart recesses 70 areprovided in the ring-like contact surface 12A which form correspondingdiscrete undercuts 28 in the sidewall 32 of the central recess 33, withboth the recesses 70 and the projections 72 of the sidewall 32 formed bythem, which form the undercuts 28, also serving for security againstrotation. This type of design of the end face is known per se, forexample from EP-B-795510 of the present applicants. There, and inEP-B-957273 the use of a wave-shaped groove in the ring-like contactsurface 12A from the generation of the undercuts 28 is also describedand can also be used here. Since wall material is here only coined intoengagement at one end face 12 of the spacer element only one die button40 is used here. Both the wall section 17A and also the wall section 17Bare pre-pierced at 46. FIG. 2B shows the situation prior to use of thedie button 40, FIG. 2C the situation thereafter.

In this embodiment the plunger 42 presses from above onto the wallsection 17B and onto the spacer element 10 and hereby presses the lowerend face 12 and the wall section 17A against the die button projection41, while the material at the rim of the hole is pressed by the diebutton into the central recess 33 and into the discrete recesses 70 aswell as into the undercuts. If the construction is so effected that thespacer element 10 is first connected to the sheet metal part 16A beforeit is connected to the sheet metal part 16B then the plunger 42 actsdirectly on the end face 14 of the spacer element 10.

One can clearly see in FIG. 2C how the sheet metal part or wall materialis formed into the recesses 70, into the undercuts 28 and into thecut-out 33 of the spacer element. The die button has precisely the shapewhich is described in EP-B-795510 and indeed with fewer noses 74 at thedie button projection 41 than recesses 70 in the end face 12A of thespacer element. In this way it is ensured that the material is pressedinto engagement in at least some recesses 70 and undercuts 28 and indeedwithout the relative rotary position of the die button 40 and the spacerelement 10 having to be determined.

It is however also possible to provide the design which is present atthe end face 12 of the spacer element according to FIGS. 2A to 2D at theend face 14. This is shown in FIGS. 3A to 3D. Through the use of thesame reference numerals in the FIGS. 3A to 3D as in FIGS. 1A to 1A and2A to 2D a separate description of the FIGS. 3A to 3D is unnecessarysince the previous description also applies in a transferred sense forFIGS. 3A to 3D.

The same applies to the FIGS. 4A to 4D which are only distinguished fromthe FIGS. 3A to 3D in that the bore 22 is not provided from the outsetwith a thread 23, with the spacer element 10 having a smoothly piercedcylindrical hole or bore which optionally is designed to receive athread-forming or thread-cutting bolt, i.e. the spacer element can alsohave here only a spacer function or an attachment function for theattachment of a further component such as 24 in FIG. 1D by means of abolt 26.

The FIGS. 5A to 5E show an alternative spacer element 10 in accordancewith the invention which is rectangular in an axial cross-section andrespectively has two bars 80 and 82 at both end faces 12, 14 with thebars extending parallel to one another and to the adjacent sides 84 ofthe spacer element and forming respective undercuts 28 at the mutuallyconfronting sides.

Between the bars there is a groove 86 at each end face of the spacerelement 10. A threaded bore 23 extends in the axial direction throughthe centre of the spacer element which, if desired, can also he squarein plane view. The die buttons 40 which are shown in FIGS. 5B and 5Ceach have a substantially rectangular die button projection 41 which canbe used for the pressing of the sheet metal material into the undercuts28. Here also the sheet metal material, or the wall material 17A, 17B ispre-pierced and indeed preferably with a rectangular hole from which twooppositely disposed wall regions 90, 92 are formed by the die buttonprojection 41 into the grooves 86 and pressed into intimate contact atthe oppositely disposed sides of each groove 86 and into thecorresponding undercuts 28. it is also possible to operate with twosheet metal parts 16A and 16B here, or a hollow section 18 can be used.The installed situation is shown in a perspective partly sectionedrepresentation in FIG. 5E. There the radii 92 can also be readilyrecognized which are formed by the radii 94 which form the transitionfrom the die button projection 41 into the planar end face of the diebutton 40. Here also—as in all embodiments—it is possible to operatewith one die button 40 or with two die buttons 40 as has been describedprecisely in connection with FIGS. 6A to 6D.

A further possibility for the design of a rectangular spacer element 10is shown in FIGS. 6A to 6D. Here the two bars 80, 82 are formed byrespective grooves 96 and indeed preferably such that both sidewalls ofeach groove 96 have a respective undercut 28. A further special featureof the embodiments in accordance with the invention of FIGS. 6A to 6Dand 7A to 7D lies in the fact that the sheet metal parts 16A and 16B orthe wall sections 17A and 17B of the hollow section are not pre-piercedbut rather the required rectangular openings are produced by the diebutton 40. This has two elongate noses extending parallel to each otherwhich are so designed that they cut, in cooperation with the adjacentend face of the spacer element 10, a rectangular piercing slug (notshown) out of the sheet metal material or out of the wall material whichis then disposed all through the central passage 99 of the die button.The reference numerals 42 signify in all drawings a tool or plungerwhich is either flat or has a cutout 44 (as shown in FIG. 6B) at theside confronting the sheet metal part or the hollow section 18 in orderto generate a reaction force on the spacer element 10 or on the sheetmetal part 16 or on the hollow section 18 when using the die buttonarranged at the opposite side of the sheet metal part 16 or the hollowsection 18. The FIGS. 7A to 7D are distinguished from those of FIGS. 6Ato 6D only in as much as the possibility of using a hollow section 18instead of the initially separated sheet metal parts 16A and 16B isshown in FIGS. 7B to 7D.

If the spacer element 10 is inserted into a finished hollow cavity 34 ofa hollow section 18 of a sheet metal part 16 then the spacer element isintroduced from the side into the hollow section and held during theattachment at the sheet metal part or hollow section 18.

It should also be brought out that the sheet metal part 16 or the hollowsection 18 is no in way restricted to the design shown here. For examplethe one sheet metal part 16A or 16B could have the shape of a top hat incross-section and the respective other part could be formed as a planarsheet metal part. The spacer element 10 could then be attached betweenthe two oppositely disposed “sides” of the top hat or between the topside of the top hat and the planar sheet metal part. Many othercross-sectional shapes of the sheet metal parts 16 or of the hollowcavity 54 are conceivable, including designs which consist of more thentwo individual sheet metal parts.

In just the same way the hollow sections 18 which are equipped with thespacer elements in accordance with the invention can have a hardlyrestricted plurality of shapes including shapes with curved wallsections 17A, 17B, which is also basically possible with sheet metalconstructions. Eventually, depending on the degree of the curvature, theend face of the spacer element could also have a curvature matchedthereto. In principle no limits are set on the length i.e. the axialheights of the spacer elements. The minimal height is however determinedby the design of the undercuts and the necessity to have a certainminimum thread length. It is however also conceivable to screwcomponents such as 24 onto two oppositely disposed sides of the sheetmetal part 16 or of the hollow section 18 and optionally to providedifferent thread sizes for this in the bore of the spacer element 10.

Summarizing the present invention makes it possible to manufacture acomponent assembly 20 consisting of a spacer element 10 which is securedat two oppositely disposed wall sections 17A, 17B of a sheet metal part16 forming a hollow cavity 54. The sheet metal part 16 can consist oftwo welded together sheet metal parts 16A, 16B. Alternatively the hollowcavity 54 can also be formed by the hollow section 18. The spacerelement 10 is designed at both ends 12, 14 for the attachment to thewall sections 17A, 17B and has, if required, a fastener section with aninternal thread or an external thread for the attachment of a component24 to the component assembly 20 by means of a bolt 26 or a nutrespectively. The spacer element has at least substantially the sameshape prior to and after the attachment and thus also the same length.The spacer element 10 is provided at both end faces 12, 14 withrespective undercuts 28 which lie behind the respective end face andinto which material of respective wall sections 17A, 17B is received inform-fitted manner, whereby the spacer element 10 is secured to the wallsections 17A, 17B and is preferably also secured in a manner secureagainst rotation. Examples for such component assemblies are to be foundin the FIGS. 1 and 3 to 7.

The invention enables the manufacture of a component assembly 20consisting of a spacer element 10 which is arranged between two mutuallyoppositely disposed wall sections 17A, 17B of a sheet metal part 16forming a hollow cavity 54. The sheet metal part 16 can consist of twowelded together sheet metal parts 16A, 16B. Alternatively to this thehollow cavity 54 can be formed by a hollow section 18. In this examplethe spacer element 10 is attached at one end to one of the wall sections17A and has a fastener section with an internal thread 23 or an externalthread for the attachment of a component 24 to the component assembly bymeans of a bolt 26 or a nut respectively.

The spacer element 10 has, prior to and after the attachment, at leastsubstantially the same shape. Furthermore, the spacer element 10 has atone end face 12 at least one undercut 28, in which material of the onewall section 17A is received in form-fitted manner, whereby the spacerelement is fastened in a rotationally secure manner at one end to thesheet metal part to one wall section. The wall section 17B lyingopposite to the last named wall section 17A has a hole 46 through whicheither a bolt 26 can be screwed into an internal thread 23 of the spacerelement 10 or through which a shaft part of the spacer element having athread projects (not shown).

In the component assemblies in accordance with the invention of FIGS. 1,2, 3 and 4 the spacer element has a central recess 34 at one end face orat each end face 12, 14 within a ring-like contact surface 12A and alsoat least one undercut 28 in the sidewall of the recess. The sheet metalmaterial of the wall section 17A and/or 17B is received in form-fittedin the undercut 28.

Component assemblies in accordance with FIGS. 2 to 4 are particularlypreferred in which a plurality of mutually spaced apart recesses 70 or agroove which is of wave-shape in plane view (not shown) are or isprovided in the ring-like contact surface 12A which form correspondinglydiscrete undercuts 28 in the sidewall of the central recess 33, withboth the discrete recesses 70 and also the wave-like groove and theprojections 72 of the sidewall, which form the undercuts 28 and whichare formed by them or by it, also serving for the security againstrotation.

As shown in FIG. 4 the component assembly in accordance with theinvention can be provided with a spacer element 10 which has a smoothlypierced cylindrical hole or bore 22 which is optionally designed toreceive a thread-forming or a thread-cutting bolt.

The component assembly in accordance with FIGS. 1A to 1D is so designedthat the undercut 28 provided there is a ring-like undercut and/or inthat the sidewall of the central recess 33 extends at leastsubstantially obliquely to the longitudinal axis so that the recess 33has, in an axial section, i.e. a plane containing the longitudinal axis,optionally the shape of a concave throat of at least substantiallyconical shape, optionally a concavely or convexly arched shape. At theend face 12, 14 of the spacer element 10 a rounded transition ispreferably present from the ring-like contact surface to the ring-likerecess. The sheet metal material of the respective wall sections 17A,17B is received in form-fitted manner in the respective undercut.

In the component assemblies in accordance with the invention with acentral recess 33 at the end face of the spacer element, featuresproviding security against rotation such as noses and/or recesses can beprovided with advantage which extend in radial planes, i.e. in planesperpendicular to the longitudinal axis, are provided at the sidewall ofthe central recess and which form corresponding recesses and/or noses inthe material of the respective wall section 17A and 17B.

Spacer elements in accordance with FIGS. 5 to 7 can be particularlycost-favourably manufactured because this can take place in a fastrunning press in a progressive tool from a section which is at leastsubstantially rectangular and this is faster than the manufacture in acold heading process, which would be necessary for the elements inaccordance with FIGS. 1 to 4. Such component assemblies arecharacterized in that a spacer element 10 is rectangular or square inthe axial cross-section and has at one end face or at both end faces twobars 80, 82 which extend parallel to one another and to the neighbouringsides 84 of the spacer element and which form respective undercuts 28 atthe mutually confronting sides. The material of the respective wallsection 17A, 17B is received in form-fitted manner in the undercuts 28.

The component assemblies in accordance with FIGS. 6 and 7 areparticularly favourable and characterized in that the two bars 80, 82are formed by respective grooves 86, in that both sidewalls of eachgroove preferably have a respective undercut 28 and in that the sheetmetal material of the respective wall sections 17A, 17B is received inform-fitted manner in these undercuts 28. This design enables the use ofa piercing die 40 for the pressing of the wall material into theundercuts 28 which however simultaneously cuts the corresponding hole inthe wall section and removes the piercing slug.

Insofar as the spacer element 10 is only secured to one side of thehollow cavity (as shown m FIG. 2) the method can also be designed insuch a way that a first sheet metal part 16A is attached to the firstend face 12 of the spacer element 10 by means of a first die button 41which presses the sheet metal material in form-fitted manner into thecorresponding undercut 28 or undercuts 28 of the first end face; that asecond sheet metal part 16B is arranged at the second end face 14 of thespacer element, with the second sheet metal part 16B having a hole 46 atthe position of the second end face 14 which is aligned with thelongitudinal axis 88 of the spacer element 10 and that the first andsecond sheet metal parts 16A, 16B are joined together or to at least onefurther sheet metal part (not shown) for the formation of a hollowcavity 54 at points 50, 52 remote from the spacer element by othermeans, for example by spot welding, mechanical joining or by furtherfastener elements or spacer elements. This other connection takes placeafter the placement of the second sheet metal part 16B at the second endface of the spacer element.

An alternative method for the manufacture of a component assembly 20 ischaracterized in that the spacer element 10 is inserted into a hollowcavity 54 of the hollow section 18 or of the sheet metal part 16 whichconsists of at least one first sheet metal part 16A and one second sheetmetal part 16B which are joined together or to at least one furthersheet metal part (not shown) for the formation of a hollow cavity, atpoints 50, 52 remote from the spacer element 10 for example byspot-welding, mechanical joining or by further fastener elements orspacer elements. This insertion takes place in such a nay that the firstand second end faces 12, 14 of the spacer element 10 lie opposite torespective first and second wall sections 17A, 17B of the hollow section18. Then, by means of a die button 40 the spacer element 10 is attachedat the first end face 12 to the first wall section 17A in that the diebutton presses material of the first wall section 17A into thecorresponding undercut 28 or undercuts 28 of the first end face 12 inform-fitted manner and such that a hole 46 in the second wall section17B lies opposite to the second end face 14 and is aligned with thelongitudinal axis 88 of the spacer element 10.

In the method of the invention the die button or both die buttons serve,during the pressing of the sheet metal material or the material of therespective wall section 17A, 17B, also for a form-fittedinter-engagement of the material and any features 30 providing securityagainst rotation.

In all embodiments all materials can be named as an example for amaterial of the spacer element which achieve the strength values ofclass 8 in accordance with the ISO standard in the context of colddeformation, for example a 35B2 alloy in accordance with DIN 1654. Theso formed spacer elements are suitable amongst other things for allcommercial steel materials for deep drawing quality sheet metal partsand also for aluminium or its alloys. Aluminium alloys in particularthose with higher strength can also be used for the spacer elements, forexample AlMg5. Spacer elements of higher strength magnesium alloys suchas for example AM50 can also be considered.

The invention claimed is:
 1. A spacer element having first and secondends, said ends being for attachment to a hollow metal part for theformation of a component assembly, wherein the spacer element is notdeformable or at least substantially not deformable on attachment towall material of a hollow metal part having first and second oppositesides or to wall material of at least one sheet metal part provided forassembly to a further sheet metal part to form a hollow metal parthaving first and second opposite sides and wherein the spacer element,having a central recess within an annular contact surface at least oneof said first and second ends, and also at least one undercut at asidewall of the central recess is provided at said first and second endswith respective undercuts for the form-fitted reception of said wallmaterial, whereby the spacer element is secured at said first and secondopposite ends to said first and second opposite sides of said hollowmetal part.
 2. A spacer element in accordance with claim 1 and having afastener section for the attachment of a component (24) to the componentassembly by means of a bolt (26) or a nut.
 3. A spacer element inaccordance with claim 1 and having means providing security againstrotation at at least one of said first and seconds ends (12, 14).
 4. Aspacer element in accordance with claim 1, wherein the undercut extendsaround said central recess at said sidewall.
 5. A spacer element inaccordance with claim 1, wherein said spacer element: has a longitudinalaxis and said central recess has a sidewall which extends at leastsubstantially obliquely to said longitudinal axis, whereby said centralrecess has a shape in an axial section corresponding to at least one ofa hollow throat, an at least: substantially conical shape, and aconcavely or convexly rounded arched shape.
 6. A spacer element inaccordance with claim 5, there being a rounded transition at at leastone of said first and second ends (12, 14) from the annular contactsurface (12A, 14A) to the central recess (33).
 7. A spacer element inaccordance with claim 1, wherein one of a plurality of mutuallyspaced-apart recesses and a groove of wave-shape in plan view isprovided in the ring-like contact surface which forms correspondingdiscrete undercuts in said sidewall, with said one of said plurality ofmutually spaced apart recesses and said wave-shaped groove, as well asand projections of said sidewall formed by it, which form undercuts insaid central recess, also serving for security against rotation.
 8. Aspacer element in accordance with claim 1, wherein elongate featuresproviding security against rotation are provided at the sidewall of thecentral recess, said elongate features being defined by at least one ofnoses and/or recesses which extend in radial planes.
 9. A spacer element(10) in accordance with claim 1 and being, one of rectangular and squarein an axial cross-section, said spacer element having first and secondbars (80, 82) at at least one of said first and second ends (12, 14),said bars extending parallel to one another and to neighbouring sides(84) of the spacer element and having mutually confronting sides, saidmutually confronting sides defining respective undercuts.
 10. A spacerelement in accordance with claim 9, wherein said mutually confrontingsides of said first and second bars are formed by respective grooveseach having first and second sidewalls and wherein said first and secondsidewalls of each groove each form a respective undercut.
 11. A spacerelement (10) in accordance with claim 1 and having a smoothly piercedcylindrical hole (22) or bore.
 12. A component assembly (20) consistingof a spacer element (10) which is secured to two oppositely disposedwall sections (17A, 17B) of a hollow metal part (16), said hollow metalpart defining a hollow cavity and consisting of first and secondwelded-together sheet metal parts (16) or being formed by the hollowspace (54) of a hollow section (18), wherein the spacer element (10) isdesigned at first and second ends (12, 14) for attachment to arespective wall section (17A, 17B), wherein the spacer element (10) hasat least substantially the same shape prior to or alter the attachmentto the sheet metal part and wherein the spacer element (10) has firstand second ends (12, 14), said ends having respective undercuts (28)into which material of the respective wall section (17A, 17B) isreceived in form-fitted manner whereby the spacer element (10) issecured to the wall sections (17A, 17B) wherein said spacer element (10)has at least one of said first and second ends (12; 14) a central recess(33) within an annular contact surface (12A, 14A), said central recess(33) having a sidewall, there being at least one undercut (28) at saidsidewall (32) of the recess (33) and wall material of the respectivewall section (17A, 17B) being received in form-fitted manner in saidundercut (28).
 13. A component assembly (20) in accordance with claim12, wherein one of a plurality of mutually spaced apart recesses (70)and a groove which is wave-shaped in a plan view is provided in thering-like contact surface (12A, 14A) and forms corresponding discreteundercuts (28) in said sidewall (32), with said one of said plurality ofmutually spaced apart recesses (70) and said wave-shaped groove as wellas projections (72) of said sidewall (32) defining said undercuts (28)and said undercuts engaging said wall material and serving for securityagainst rotation.
 14. A component assembly (20) in accordance with claim12, wherein said fastener section is provided with at least one of aninternal thread, an external thread and a smooth pierced cylindricalhole or bore (22).
 15. A component assembly (20) in accordance withclaim 12, wherein each said undercut is an annular undercut (28) inwhich sheet metal material is received.
 16. A component assembly inaccordance with claim 12, wherein at least one of said ends (12; 14) hasa central recess having a sidewall and a central longitudinal axis andwherein said sidewall (32) extends at least substantially obliquely tosaid longitudinal axis, whereby said central recess (33) has a shape inan axial section corresponding to at least one of a concave throat, anat least substantially conical shape, and a concavely or convexlyrounded arched shape and wherein sheet material of the respective wallsections (17A, 17B) is received in form-fitted manner in the respectiveundercut (28).
 17. A component assembly (20) in accordance with claim12, wherein each of said first and second ends has a central axis havinga sidewall and wherein elongate features providing security againstrotation formed by at least one of noses (30) and recesses which extendin radial planes at the sidewall (32) of the central recess (33) areprovided, said elongate features forming complementary features of shapein the material of the respective wall section (17A, 17B).